2003年秋季青海省河南县地面大气冰核观测分析
Observation and Analysis on Ice Nucleus of Henan County of Qinghai Province in Autumn 2003
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摘要: 利用Bigg型混合云室对2003年10月5—26日青海省河南县的地面大气冰核进行了观测, 并将结果同该地区前两年的结果以及其他高原地区的观测结果进行比较, 发现: ①该地区大气冰核的平均浓度高于往年, 冰核浓度随温度降低而增加、斜率小于该地区前两年的观测, 冰核平均浓度的分布更加趋于集中; ②由于霰和高原夜雨的经常出现, 降水对冰核浓度有不确定的影响; ③冰核平均浓度与气压和湿度分别呈现反相关与正相关趋势; ④风对冰核浓度有影响, 低温核随风向的变化比高温核大; ⑤人类活动对冰核浓度也有影响。Abstract: Natural ice nucleus in atmosphere are one of the basic conditions for the ice crystal formation, which can exert a key influence on the cold cloud precipitation. In addition, many researches on ice nucleus show that ice nucleus play the same important role in the various weather processes as the cloud condensation nucleus. Besides the influence on the microphysical structure of cold cloud and precipitation, ice nucleus concentration affects the radiation characteristics of cloud and then influences the weather and climate processes accordingly. In order to understand the physical mechanism of the precipitation and microphysical background of rainfall enhancement in China, the observation on ice nucleus is carried out and a lot of useful results are gained since 1960. However, up to now, most researches focus on different areas, the continuous observations on the same area, the same period and using the same method are few, especially over Tibet Plateau. To highlight the characteristics of the ice nucleus over Tibet Plateau area (Henan County in Qinghai Province), some useful results for the further understanding on the precipitation mechanism and weather and climate processes are provided. In terms of the Bigg mixing chamber in which the valid volume of the chamber is 3.05 liter the ice nucleus are observed from October 5 to 26 in 2003. On the bottom of the chamber, there is the sugar plate whose diameter is 10 centimeter. The super cold fog is formed manually, which can last 2—3 minutes. The ice nucleus form little crystals falling down to the sugar plate, increase until they can be distinguished by eye, then the sugar plate is pulled up to count the crystals number, so the ice nucleus concentration is obtained. This method is applied in the observation of ice nucleus over Tibet Plateau in the year of 1989, 2000, 2001, 2002. Also, the observations are compared with that gained in last two years in the target area and other plateau areas. Results show that: ① The concentration of ice nucleus over the plateau is greater than previous while the distribution slope is smaller, and the distribution of ice nucleus is inclined to evenness; ② The graupel and rainfall during night contribute to the uncertainty of ice nucleus concentration; ③ The relation between the concentration of ice nucleus and the pressure is negative while the relation between the concentration of ice nucleus and humidity is positive; ④ Wind influence on concentration of ice nucleus and the variety of ice nucleus in low temperature is larger than that in the high temperature; ⑤ Human activity may have influence on the concentration of ice nucleus.
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表 1 2001, 2002, 2003年青海省河南县冰核浓度观测结果比较
表 2 我国青海高原地区冰核温度谱参数
表 3 青海河南县2000—2003年平均逐月降水量和降水日数
表 4 观测期间风向出现频数
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